Class: Omnizip::Formats::Ole::RangesIO

Inherits:
Object
  • Object
show all
Defined in:
lib/omnizip/formats/ole/ranges_io.rb

Overview

Virtual IO for non-contiguous byte ranges

Provides a contiguous IO interface over scattered byte ranges in an underlying IO object.

Direct Known Subclasses

RangesIOResizeable

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(io, ranges = []) ⇒ RangesIO

Initialize RangesIO

Parameters:

  • io (IO) —

    Underlying IO object

  • ranges (Array<Array<Integer, Integer>>) (defaults to: []) —

    Byte ranges



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# File 'lib/omnizip/formats/ole/ranges_io.rb', line 27

def initialize(io, ranges = [])
  @io = io
  @pos = 0
  @active = 0
  self.ranges = ranges
end

Instance Attribute Details

#io ⇒ IO (readonly)

Returns Underlying IO object.

Returns:

  • (IO) —

    Underlying IO object



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# File 'lib/omnizip/formats/ole/ranges_io.rb', line 12

def io
  @io
end

#pos ⇒ Integer Also known as: tell

Returns Current position.

Returns:

  • (Integer) —

    Current position



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# File 'lib/omnizip/formats/ole/ranges_io.rb', line 21

def pos
  @pos
end

#ranges ⇒ Array<Array<Integer, Integer>>

Returns Byte ranges [[offset, length], ...].

Returns:

  • (Array<Array<Integer, Integer>>) —

    Byte ranges [[offset, length], ...]



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# File 'lib/omnizip/formats/ole/ranges_io.rb', line 15

def ranges
  @ranges
end

#size ⇒ Integer (readonly)

Returns Total size in bytes.

Returns:

  • (Integer) —

    Total size in bytes



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# File 'lib/omnizip/formats/ole/ranges_io.rb', line 18

def size
  @size
end

Class Method Details

.open(io, ranges = []) {|RangesIO| ... } ⇒ Object

Open with block support

Yields:



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# File 'lib/omnizip/formats/ole/ranges_io.rb', line 37

def self.open(io, ranges = [])
  ranges_io = new(io, ranges)
  if block_given?
    begin
      yield ranges_io
    ensure
      ranges_io.close
    end
  else
    ranges_io
  end
end

Instance Method Details

#close ⇒ Object

Close and free resources



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# File 'lib/omnizip/formats/ole/ranges_io.rb', line 230

def close
  free
end

#eof? ⇒ Boolean

Check if at end

Returns:

  • (Boolean) 


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# File 'lib/omnizip/formats/ole/ranges_io.rb', line 131

def eof?
  @pos == @size
end

#free ⇒ void

This method returns an undefined value.

Free resources to prevent memory leaks



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# File 'lib/omnizip/formats/ole/ranges_io.rb', line 79

def free
  @io = nil
  @ranges = nil
  @offsets = nil
end

#inspect ⇒ Object

Inspect



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# File 'lib/omnizip/formats/ole/ranges_io.rb', line 235

def inspect
  "#<#{self.class} io=#{@io.inspect}, size=#{@size}, pos=#{@pos}>"
end

#read(limit = nil) ⇒ String

Read data

Parameters:

  • limit (Integer, nil) (defaults to: nil) —

    Maximum bytes to read

Returns:

  • (String) 


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# File 'lib/omnizip/formats/ole/ranges_io.rb', line 139

def read(limit = nil)
  data = "".b
  return data if eof?

  limit ||= @size
  return data if limit <= 0

  range_pos, range_len = @ranges[@active]
  diff = @pos - @offsets[@active]
  range_pos += diff
  range_len -= diff

  loop do
    @io.seek(range_pos)

    if limit < range_len
      chunk = @io.read(limit).to_s
      @pos += chunk.length
      data << chunk
      break
    end

    chunk = @io.read(range_len).to_s
    @pos += chunk.length
    data << chunk

    break if chunk.length != range_len

    limit -= range_len
    break if @active >= @ranges.length - 1

    @active += 1
    range_pos, range_len = @ranges[@active]
  end

  data
end

#rewind ⇒ Object

Rewind to beginning



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# File 'lib/omnizip/formats/ole/ranges_io.rb', line 124

def rewind
  seek(0)
end

#truncate(_size) ⇒ Object

Truncate (not supported by default)

Parameters:

  • _size (Integer) —

    New size

Raises:

  • (NotImplementedError) 


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# File 'lib/omnizip/formats/ole/ranges_io.rb', line 225

def truncate(_size)
  raise NotImplementedError, "truncate not supported"
end

#write(data) ⇒ Integer Also known as: <<

Write data

Parameters:

  • data (String) —

    Data to write

Returns:

  • (Integer) —

    Bytes written



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# File 'lib/omnizip/formats/ole/ranges_io.rb', line 181

def write(data)
  data = data.dup.force_encoding(Encoding::ASCII_8BIT) if data.is_a?(String)
  return 0 if data.empty?

  # Grow if needed
  if data.length > @size - @pos
    truncate(@pos + data.length)
  end

  range_pos, range_len = @ranges[@active]
  diff = @pos - @offsets[@active]
  range_pos += diff
  range_len -= diff

  written = 0

  loop do
    @io.seek(range_pos)

    if written + range_len > data.length
      chunk = data[written..]
      @io.write(chunk)
      @pos += chunk.length
      break
    end

    @io.write(data[written, range_len])
    @pos += range_len
    written += range_len

    break if @active >= @ranges.length - 1

    @active += 1
    range_pos, range_len = @ranges[@active]
  end

  data.length
end